The invention relates to a sensor having a substrate which supports a magnetic field-sensitive element in thin-film form, in which the magnetic field-sensitive element is deposited on a side wall of a groove extending in a surface of the substrate, and in which necessary leads are present to connect electric connections of the magnetic field-sensitive element to external circuits.
The invention also relates to a method of manufacturing a sensor having a magnetic field-sensitive element. A sensor having a magnetic field-sensitive element is known from U.S. Pat. No. 4,151,574 in the manufacture of which a groove having a defined shape is provided in a surface of a substrate, after which an auxiliary layer is deposited on the surface of the substrate on either side of the groove and on one wall of the groove at a first angle with the substrate, a layer of magnetic field-sensitive material is deposited on the auxiliary layer on either side of the groove and on the wall of the groove present opposite to said wall at a second angle with the substrate, the auxiliary layer with the magnetic field-sensitive material present thereon is then etched away, and the layer of magnetic field-sensitive material remaining on one wall of the groove is connected to electrical leads.
In the method used of vapor-depositing at an angle in which moreover the two oppositely located walls of the groove extend obliquely to the substrate surface, a magnetic field-sensitive element of uniform thickness cannot be provided on one of the walls while using the shadow effect of the other wall. This means that a sensor manufactured by means of the known methods cannot have a magnetic field-sensitive element which extends at right angles to the substrate surface and has a uniform thickness. However, for many applications, a perpendicular position is required because only then it is possible to measure one given component of a magnetic field. With an oblique position of the element, this cannot be done because then the substrate surface can no longer serve as an alignment reference.
A further disadvantage of the method used of vapor deposition at an angle is that the height of the magnetic field-sensitive element cannot be adjusted accurately. A spreading of 0.5 .mu.m has to be taken into account as a result of which elements having a height smaller than 5 microns cannot be manufactured with sufficient accuracy. Sensors having magnetic field-sensitive elements with a height smaller than 5 microns, and in particular smaller than 1 micron, are required, however, to measure magnetic fields which span very small regions in the micron range. For example, magnetic elements having a height smaller than one micron are required for measuring the stray fields of a magnetic bubble or measuring the write field of a magnetic head.
The above also means that the lower edge of the vapor-deposited element must be spaced by at least 0.5 microns from the bottom of the groove so as to prevent magnetic field-sensitive material being also deposited on the bottom of the groove. In fact, this material is not also removed upon lifting the auxiliary layer. In that case, the element would consist of two parts not situated in one plane and would, hence, also be sensitive to magnetic field components having different directions. Thus, it is not possible to use the depth of the groove (to be proportioned accurately) for adjusting the height of the element.